Bearing mounting arrangements have been utilized for many years on lift mast assemblies in a variety of ways. In one application, the bearing mounting arrangement is utilized to pivotally attach the lift mast assembly to the material handling vehicle so that the lift mast assembly may pivot about a transverse vehicle axis. An example of such a bearing mounting arrangement is shown in U.S. Pat. No. 3,556,247 to Akibumi Shinoda, dated Jan. 19, 1971. The Shinoda patent discloses a sleeve bearing and a two piece connecting flange mounted on an upright of the lift mast assembly. The two piece flange pivotally connects the lift mast assembly to the material handling vehicle.
Frequently, the sleeve bearing is disposed between the two piece connecting flange and a cylindrical supporting flange. An example of a cylindrical supporting flange is a drive axle housing connected to the frame of the material handling vehicle. U.S. Pat. No. 4,100,986 to William M. Shipitalo, dated July 18, 1978 discloses a such a mounting arrangement. In either patent disclosure the sleeve bearing slidably rotates on the cylindrical supporting flange during pivoting of the mast assembly.
Due to the absence or lack of adequate lubricant in the area of sliding movement of the sleeve bearing premature wearing of the sleeve bearing and the cylindrical supporting flange occurs. This premature wear causes looseness in the connection and affects the operation of the lift mast assembly in a number of ways. For example, a sloppy connection will place excessive side loading on the tilt jacks and cause fluid leakage and tilt jack failure. The loose connection also reduces the vehicle operators ability to accurately position the lift mast assembly and load engaging fork. Thus an increase in load cycle time and a reduction in thruput occurs.
Bearing mounting arrangements are also used in a side shift carriage applications to provide relatively free sliding movement of a side shiftable frame relative to a carriage frame. The bearing mounting arrangement typically connects a plain bearing member to the side shiftable frame and maintains the plain bearing member from transverse movement relative to the side shiftable frame. Due to the absence or lack of adequate lubricant to the proper surface of the plain bearing member the potential for premature wear of the plain bearing member and the carriage frame occurs. Premature wear of the plain bearing causes rubbing and binding of the side shiftable frame relative to the carriage frame. This results in a reduction in the ease of movement of the side shiftable frame and ultimately causes failure of the side shift carriage.
In order to alleviate premature wear of either of the above discussed bearings it is necessary to direct lubricant to the surface of the bearing which bears against the relatively movable frame portion (the cylindrical supporting flange or the carriage frame). In an attempt to solve the problem a hole was provided in the sleeve bearing to pass lubricant from a passage in the connecting flange through the sleeve bearing and to the appropriate side of the sleeve bearing. During operation it was found that the majority of the lubricant would follow the path of least resistance and exit the bearing at the wrong side. It was discovered that over time, dirt and hardened lubricant would plug the hole and cause new fresh lubricant to be blocked from passing to the proper side of the bearing. From visual inspection it appeared that the lubricant was flowing to the proper location, however, premature wear and further inspection after tear down of the bearing mounting arrangement proved otherwise.
In the aforementioned applications the bearings were retained from movement relative to the stationary members (carriage frame and connecting flange) by complicated fastening arrangements. These arrangements included closely toleranced dowel and pin fits, sophisticated bearing carriers and the like. Such retaining methods are expensive to manufacture and less than totally successful in retaining the bearing.
The present invention is directed to overcoming one or more of the problems as set forth above.